Developmental Study of Highly-Uniform Large-Diameter ECR Plasma Reactor

本研究的目的是发展一个大直径的电子回旋共振（ECR）等离子体源，用于12英寸晶片的高速加工。我们已经构建了一个多环（MA）天线，它包括一个同心阵列的环形狭缝的微波辐射和永磁体的多环会切磁场。2.45GHz的微波通过同轴线馈送，并被分配到环形狭缝中，以遇到位于狭缝出口之外5 mm处的ECR层。在多环会切场中，带电粒子沿方位角方向漂移。这导致方位角对称的等离子体产生。微波以R波的形式从狭缝向ECR层传播。使用该MA天线的等离子体源在Ar气体压力为5 × 10 - 4托的情况下产生了直径为30 cm、密度n = 2 × 10 - 4 cm-1的等离子体<11><-3><-4>。我们通过改变狭缝的数量来测量等离子体参数，发现在最外侧位置的一个狭缝的等离子体的均匀性最好。对于直径为30 cm的等离子体，在距离MA天线10 cm处的均匀性为 *10%，其中n =（8-10）*10 μ <10>cm<-3>。将MA天线改进为AMA（adjustable MA）天线，它有两个环形狭缝，狭缝的半径分别为140和90 mm，每个狭缝由磁控管独立驱动。这意味着微波功率输入的径向分布可以通过简单地改变两个磁控管的输出来调节。通过使用AMA天线，我们实现了在离天线较短的距离内产生更高密度、更高均匀性的等离子体。

The purpose of this research is to develop a large diameter electron cyclotron resonance (ECR) plasma source for high-speed processing of 12 inch wafers. We have constructed a multi-annular (MA) antenna which consists of a concentric array of annular slits for microwave irradiation and of permanent magnets for multi-ring cusp magnetic field. The microwave at 2.45 GHz is fed via coaxial line and is distributed into the annular slits to encounter the ECR layr located 5 mm beyond the exit of the slits. Charged particles drift in azimuthal direction in the multi-ring cusp field. This leads to azimuthally symmetric plasma production. The microwave propagates from the slit to the ECR layr from high magnetic field side as R-waves. It is noted that the plasma is not produced inside the slits because the loss rate of charged particles is large due to proximity of slit walls.The plasma source using this MA antenna has produced a plasma of 30 cm in diameter with density n = 2*10^<11>cm^<-3> for Ar gas pressure 5*10^<-4> Torr. We measured plasma parameters by changing the number of the slits to find that the uniformity of the plasma is best for one slit at the outermost location. The uniformity is *10% for 30 cm diameter plasma with n = (8-10)*10^<10>cm^<-3> at 10 cm from the MA antenna. This result is consistent with a numerical calculation of the equation of continuity assuming an initial source profile determined by the slits.The MA antenna has been improved to AMA (adjustable MA) antenna, which has two annular slits at r =140 and 90 mm. Each slit is driven by a magnetron independently. This means that the radial profile of microwave power input is adjustable by simply changing the outputs of two magnetrons. By using AMA antenna, we have achieved plasma production with higher density, higher uniformity at shorter distance from the antenna.